Let the \textbf{ kernel density estimator} be:

\[   \hat{f}_h(x) = \frac{1}{|A|}\sum_{ y \in A} K_h (T_d(x,y))  \]

 where $K_h(x) \simeq \exp( -x^2/h^2)$ is the Gaussian Kernel of bandwidth $h>0$ (the value of $h$ remains to be determined).


